The present invention relates to a combustion type waste gas treatment system for combustion-treating hazardous and combustible waste gases discharged from semiconductor manufacturing systems, liquid crystal panel manufacturing systems, etc. More specifically, the present invention relates to a combustion type waste gas treatment system for combustion-treating hazardous and combustible waste gases containing, for example, silane gas (SiH4) or a halogen-containing gas (NF3, CF3, SF6, CHF3, C2F6, CF4, etc.), or hardly decomposable waste gases.
A conventional combustion type waste gas treatment system has a burner part and a combustion chamber provided at the downstream side of the burner part. An auxiliary burning gas is supplied into the burner part and burned to form flames, and a hazardous and combustible waste gas introduced into the burner part is burned with the flames. Regarding the auxiliary burning gas, hydrogen gas, city gas, propane gas or the like is used as fuel gas, and oxygen or air is usually used as an oxidizing agent.
To oxidatively decompose a hazardous and combustible waste gas efficiently under heating in such a combustion type waste gas treatment system, it is desirable that the treatment system have a structure which allows the waste gas flowing into the burner part and the combustion chamber to mix thoroughly with other combustion gas and permits the waste gas to stay in the combustion chamber for a lengthened period of time and which facilitates heating of the waste gas. Conventional waste gas treatment systems of the type described above are not satisfactory in terms of the resident time of waste gas and the scheme of heating waste gas.
In the above-described combustion type waste gas treatment system, because the waste gas is combustible, there is a danger of backfire spreading into a waste gas inlet pipe for introducing the combustible waste gas into the burner part, which may cause devices to be broken. There is also a danger of pressure rise due to abnormal combustion, which may also cause breakage of devices. Further, there is a danger that fuel gas or oxygen gas may leak from the fuel gas supply line or the oxygen gas supply line. When hydrogen gas is used as fuel gas in particular, leakage of hydrogen gas and oxygen gas may cause an explosion. Therefore, there is a demand for implementation of a combustion type waste gas treatment system capable of coping with these dangers and stabilizing the combustion of the auxiliary burning gas and hence capable of combustion-treating waste gas safely and efficiently.